Method of manufacturing metal tubes.



R; ALLEN.

METHOD OF MANUFACTURING METAL TUBES.

APPLICATlON FILED JULY 2,1913.

1,324,714. Patented Dec. 9,1919.

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R. ALLEN.

' METHOD OF MANUFACTURING METAL TUBES.

APPLICATION FILED JULY 2.1913- 1324 714. Patented Dec. 9,1919.

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' GHOW unrrnn STA ROBERT ALLEN, F CAVERSHAM, ENGLAND.

METHOD OF MANUFACTURING METAL TUBES.

Specification of Letterslatent.

Patented Dec. 9, 1919.

Application filed July 2, 1918. Serial No, 777,09.

ments in Methods of Manufacturing Metal Tubes, of which the following is a specification.

This invention relates to a method of manufacturing metal tubes for heaters, su-

" perheaters and other surface apparatus,

and has special reference to tubes provided with helical internal and external ribs.

The object of the invention is'to provide an improved and inexpensive method of manufacturing tubes of the above mentioned character, and one by which the tubes will be strong and durable and capable of bein used eifectively for the purpose for whic they are designed.

In one method of constructing the tubes with internal and external spiral ribs according to this invention, each tube is formed by winding one or more cross irons or T irons helically around .a suitable mandrel and welding the windings. together, or a series of pairs of opposed ribs ma be formed on a plate sufliciently wide to form the tube with a single winding.

In another method of constructing the tubes, spiral ribs projecting both inside and outside the tubes are welded to the tubes, each tube being preferably provided with three or more spiral ribs of ra id pitch. The tubes with triple ribs are ormed by winding three flat metal strips helically on a suitable mandrel leaving three helical spaces into which the ribs formed of flat stri s curved edgewise are inserted so as to pro ect both inside and outside the tube, the helical ribs being then secured, and the joints closed by electric welding or other means. 1

The invention is hereinafter described with reference to the accompanying drawin in which, Y Y

gigures 1 and 2 are elevation and long1- tudinal section respectively of a tube wlth spiral ribs, and- Fig. 3 illustrates in plan and transverse section a ribbed plate from which the tube is formed. I 4

Figs. land 2 show the complete tubes a formed with the internal and external ribs 6. These tubes are madein various ways, and I will proceed to describe one convenient method with reference to Fig. 3. A solid plate is taken and machined or rolled to the shape shown, that is, longitudinal integral ribs are produced by rolling or by cutting awa portions on opposite sides of the plate, t ese ribs terminating at a short distance from the ends of the plate which are cut at an angle. The plate is then heated and forced around a helically grooved mandrel to form the tube shown 1n Figs. 1 and 2, the joint being autogenous welded.

By mserting rods in the centers of the tubes to close the passage between the ribs the whole of the gases can be compelled to flow in a helical course through the tubes.

What I claim and desire to secure by Letters Patent is 2- 1. A method of manufacture of metal tubing with helical internal and external integral ribs, consistin in first forming the ribs on a metal blani, then winding the blank helically around 'a mandrel, and finally welding the whole together into tube form. t

2. A method. of manufacture of metal tubes having opposed internal and external helical 'ribs integral therewith, consisting in formin ribs on opposite faces of a straight meta blank, winding the ribbed blank helically around a mandrel, and joining the whole of the convolutions together to form a continuous length of tubing.

3. A method of manufacturing a metal tube with a helical-internal passage and external helical ribs consisting in windin a metal strip with opposed ribs aroun a mandrel, withdrawing the mandrel and inserting filling means in the central portion of the tube unoccupiedby the ribs.

4. The method of manufacturing a tube having helical passages therein, consisting in providing a strip with parallel ribs extending along one of its sides, bend' the strip helicall so that said ribs exten inward and t e longitudinal edges of the strip abut against one another, and sealing the joint formed by the meeting edges of said strip.

5.'The method of manufacturing a tube having helical passages therein, consisting in providing a strip with arallel ribs extending along one of its si es, bending the strip helically so that said ribs extend inward and the longitudinal edges of the strip abut against one another, sealing the joint formed by the meetingedges of said strip, and securing a cylindrical core to the inner edges of the ribs in a manner to separate the passagesfrom one another and from the space encompassed by said ribs.

6. The method of forming a tube with a helical rib, consisting in formin a strip with a rib projecting from one 0 its sides eeann and extending longitudinally thereof, winding the strip helically and thereby causing its longitudinal edges to meet one another, and sealing the joint at the meeting edges.

In testimony whereof I have aflixed my signature, in presence of two witnesses.

ROBERT ALLEN.

Witnesses BENJ. TULL, J OHN UTLEY. 

